1. Field of the Invention
The present invention relates to a method for making a transparent carbon nanotube film.
2. Discussion of Related Art
Carbon nanotubes have been well known for their special properties ever since they've been discovered. Many potential applications have been proposed for carbon nanotubes, including conductive and high-strength composites, energy storage and energy conversion devices, sensors, field emission displays, and nanometer-sized semiconductor devices, referring to “Carbon Nanotubes-the Route Toward Applications” (Science, 297, 787 (2002)).
Carbon nanotube film has been found to be especially useful in field emission electron sources, photoelectric and biological sensors, transparent electrical conductors, battery electrodes, absorbing materials, water purification materials, light emitting material, and related devices. Thus, methods for making carbon nanotube films have become the basis for applications in the above-described fields. Currently, carbon nanotube films can be made via a method of direct growth.
Carbon nanotube film can also be made by methods using carbon nanotube powders, such as a dropping and drying solvent method, a Langmuir-Blodgett (L-B) method, a printing method, an electrophoresis method, and a membrane filter method, among other methods. Carbon nanotube film can also be pulled out from super-aligned carbon nanotube arrays and the carbon nanotubes in the carbon nanotube film are aligned in parallel to each other and combined together by van der Waals attractive force therebetween.
The carbon nanotubes in the carbon nanotube films made by above-described methods are typically in the form of big bundles. Thus, a light transmittance of the carbon nanotube films is less than 75%.
What is needed, therefore, is a method for making a transparent carbon nanotube film with high light transmittance.